Quote Service

This service is responsible for calculating shipping costs, based on the number of items to be shipped. The quote service is called from Shipping Service via HTTP.

The Quote Service is implemented using the Slim framework and php-di for managing the Dependency Injection.

The PHP instrumentation may vary when using a different framework.

Quote service source


Initializing Tracing

In this demo, the OpenTelemetry SDK has been automatically created as part of SDK autoloading, which happens as part of composer autoloading.

This is enabled by setting the environment variable OTEL_PHP_AUTOLOAD_ENABLED=true.

require __DIR__ . '/../vendor/autoload.php';

There are multiple ways to create or obtain a Tracer, in this example we obtain one from the global tracer provider which was initialized above, as part of SDK autoloading:

$tracer = Globals::tracerProvider()->getTracer('manual-instrumentation');

Manually creating spans

Creating a span manually can be done via a Tracer. The span will be default be a child of the active span in the current execution context:

$span = Globals::tracerProvider()
/* calculate quote */

Add span attributes

You can obtain the current span using OpenTelemetry\API\Trace\Span.

$span = Span::getCurrent();

Adding attributes to a span is accomplished using setAttribute on the span object. In the calculateQuote function 2 attributes are added to the childSpan.

$childSpan->setAttribute('app.quote.items.count', $numberOfItems);
$childSpan->setAttribute('app.quote.cost.total', $quote);

Add span events

Adding span events is accomplished using addEvent on the span object. In the getquote route span events are added. Some events have additional attributes, others do not.

Adding a span event without attributes:

$span->addEvent('Received get quote request, processing it');

Adding a span event with additional attributes:

$span->addEvent('Quote processed, response sent back', [
    'app.quote.cost.total' => $payload


In this demo, metrics are emitted by the batch trace and logs processors. The metrics describe the internal state of the processor, such as number of exported spans or logs, the queue limit, and queue usage.

You can enable metrics by setting the environment variable OTEL_PHP_INTERNAL_METRICS_ENABLED to true.

A manual metric is also emitted, which counts the number of quotes generated, including an attribute for the number of items.

A counter is created from the globally configured Meter Provider, and is incremented each time a quote is generated:

static $counter;
$counter ??= Globals::meterProvider()
    ->createCounter('quotes', 'quotes', 'number of quotes calculated');
$counter->add(1, ['number_of_items' => $numberOfItems]);

Metrics accumulate and are exported periodically based on the value configured in OTEL_METRIC_EXPORT_INTERVAL.


The quote service emits a log message after a quote is calculated. The Monolog logging package is configured with a Logs Bridge which converts Monolog logs into the OpenTelemetry format. Logs sent to this logger will be exported via the globally configured OpenTelemetry logger.